Content and Yield of L-DOPA and Bioactive Compounds of Broad Bean Plants: Antioxidant and Anti-Inflammatory Activity In Vitro.

The broad bean plant contains L-DOPA, a compound that is essential for patients with Parkinson's disease. However, little has been reported on other broad bean compounds that have beneficial effects on health. The objective was to evaluate plants of four Mexican broad bean varieties to determine the content and yield of total phenolic compounds (TPC), total flavonoids (TF), and L-DOPA, as well as to analyze the flavonoid profile and antioxidant (AA) and anti-inflammatory (AANTI) activity in vitro. Broad bean seeds were sown in the field and plants were harvested 20 days after emergence. The analyses were performed with visible UV spectrophotometry and HPLC. The variety José María produced the highest yield of TPC (9.30 g m-2), TF (8.08 g m-2), and L-DOPA (5.64 g m-2) per unit of area. The highest yields per plant were obtained with the Rojita variety: TPC (0.25 g plant-1), TF (0.21 g plant-1), and L-DOPA (0.17 g plant-1). This variety also had the highest antioxidant (IC50 = 87.68 µg mL-1) and anti-inflammatory (IC50 = 74.40 mg mL-1) activity, which was attributed to the L-DOPA compounds and to rutin and isoorientins, respectively. The flavonoid profile revealed the presence of rutin and isoorientins, which had not been previously detected in the broad bean plant.

Phytoremediation assisted by mycorrhizal fungi of a Mexican defunct lead-acid battery recycling site.

A field experiment was conducted during 15 months to study the effects of four arbuscular mycorrhizal fungi (AMF) on the growth of Ricinus communis accession SF7. Plants were established on amended soil (vermicompost:sawdust:soil 1:1:1) severely polluted by lead-acid batteries (LAB) located at Mexico State, Mexico. Plants inoculated with Acaulospora sp., Funneliformis mosseae and Gigaspora gigantea had 100% survival in comparison to non-inoculated plants (57%). These same AMF enhanced palmitic and linoleic acids content in seeds of R. communis. Acaulospora sp. modified rhizosphere soil pH and decreased 3.5 folds Pb foliar concentrations while F. mosseae BEG25 decreased three times Pb soil availability in comparison to non-inoculated plants. Spatial changes in Pb soil availability were observed at the end of this research. No fungal effect on P, Ca, Cu foliar concentrations, soluble sugars, proline, chlorophyll or on the activity of two oxidative stress enzymes was observed. Mycorrhizal colonization from the inoculated fungi was between 40% and 60%, while colonization by native fungi was between 16% and 22%. A similar percentage of foliar total phenolic compounds was observed in non-mycorrhizal plants and those inoculated with G. gigantea and Acaulospora sp. This is the first research reporting effects of AMF on R. communis (castor bean) shrubs when grown on a LAB recycling site suggesting the use of Acaulospora sp. and F. mosseae BEG25 in phytostabilization to ameliorate Pb pollution and decreasing its ecological risk.

Biological activity of Claviceps gigantea in juvenile New Zealand rabbits.

The Ascomycete fungus Claviceps gigantea infects maize kernels and synthetizes several alkaloids, mostly dihydrolysergamides. There is limited information on the damage these toxins cause in mammals, despite reports from infested areas with 90% presence of the fungus sclerotia. With this background, it was decided to determine the biological activity of chemical compounds present in sclerotia of C. gigantea in rabbits 38 days after weaning. Sclerotia of C. gigantea were collected in fields with high incidence of the disease, ground and analysed for nutrients. Experimental diets were prepared with four treatments, where sclerotial powder was added, substituting for alfalfa flour in increasing proportions [C. gigantea/alfalfa flour (0:100, 5:95, 15:85 and 25:75)]. Total ergot alkaloid content was analysed by high-performance liquid chromatography. Male juvenile rabbits were utilised and distributed in completely randomised design with four replications. Initial weight was recorded in each animal, and experimental diet was offered. In this study, weight of animals, feed consumption and feed conversion were evaluated in individual animals. Blood samples were taken for haemograms, and finally euthanasia was practiced. The consumption of C. gigantea had a negative effect on body weight and feed consumption. The necropsies showed anomalies proportional to the consumption of feed contaminated with the fungus.

Riparian plants on mine runoff in Zimapan, Hidalgo, Mexico: Useful for phytoremediation?

Dispersion and runoff of mine tailings have serious implications for human and ecosystem health in the surroundings of mines. Water, soils and plants were sampled in transects perpendicular to the Santiago stream in Zimapan, Hidalgo, which receives runoff sediments from two acidic and one alkaline mine tailing. Concentrations of potentially toxic elements (PTE) were measured in water, soils (rhizosphere and non-rhizosphere) and plants. Using diethylenetriaminepentaacetic acid (DTPA) extractable concentrations of Cu, Zn, Ni, Cd and Pb in rhizosphere soil, the bioconcentration and translocation factors were calculated. Ruderal annuals formed the principal element of the herbaceous vegetation. Accumulation was the most frequent strategy to deal with high concentrations of Zn, Cu, Ni, Cd and Pb. The order of concentration in plant tissue was Zn>Pb>Cu>Ni>Cd. Most plants contained concentrations of PTE considered as phytotoxic and behaved as metal tolerant species. Rorippa nasturtium-aquaticum accumulated particularly high concentrations of Cu. Parietaria pensylvanica and Commelina diffusa, common tropical weeds, behaved as Zn hyperaccumulators and should be studied further.

Distribución potencial y características geográficas de poblaciones silvestres de Vanilla planifolia(Orchidaceae) en Oaxaca, México / Potential distribution and geographic characteristics of wild populations ofVanilla planifolia(Orchidaceae) Oaxaca, Mexico

ResumenLos especímenes silvestres de Vanilla planifolia G. Jack forman parte del acervo genético primario, los cuales solo se han reportado en Oaxaca, México. Por ello se evaluó la distribución de esta especie con el objetivo de ubicar y describir características ecológicas en zonas potenciales de distribución. La metodología empleada consistió de cuatro etapas: 1) Elaboración de una base de datos con registros de herbario;2) Construcción de la distribución potencial basado en los registros históricos de herbario para la especie, mediante el modelo de máxima entropía (Maxent), con el uso de 22 variables bioclimáticas como predictoras; 3) Realización de búsquedas sistemáticas de individuos in situ con base en los registros de herbario y las áreas de distribución potencial en 24 municipios, para conocer la situación y la distribución del hábitat actual, y 4) Descripción mediante factores ambientales de los nichos ecológicos potenciales generados por MaxEnt. La revisión de las colecciones de herbarios reportó un total de 18 registros de V. planifolia, comprendidos entre 1939 y 1998.La búsqueda sistemática de individuos en campo ubicó 28 plantas distribuidas en 12 sitios sobre 95 364 Km2. Las variables que contribuyeron con mayor valor porcentual para determinar la estimación del modelo de distribución potencial en vainilla son precipitación del periodo más lluvioso (61.9 %), régimen de humedad del suelo (23.4 %) y precipitación del cuatrimestre más lluvioso (8.1 %). El hábitat potencial de la especie se distribuyó en cuatro zonas; trópico húmedo del golfo de México, templado húmedo, trópico húmedo y templado húmedo del pacifico. La precipitación anual osciló de 2 500 a 4 000 mm, con lluvias en verano y porcentaje de precipitación invernal de 5 a 10 %. El régimen de humedad y clima predominantes fueron údico tipo I (330 a 365 días de humedad) y cálido húmedo (Am/A(C) m). Las plantas se ubicaron en altitudes de 200 a 1 190 msnm, en laderas accidentadas, que por lo general están al pie de sistemas montañosos de 1 300 a 2 500 metros de altitud. En condiciones naturales la distribución de la especie no se limita a selva alta perennifolia, dado que se ubicó en bosque mesófilo de montaña y bosque tropical perennifolio. La ubicación de nuevos especímenes de V. planifolia en condiciones silvestres reduce un 66 % del área potencial de distribución, y la fragmenta, al pasar de ser una zona continua a convertirse en tres zonas geográficamente separadas. La reducción del hábitat se debió a un aumento en el número de plantas ubicadas, lo que define las condiciones ambientales a un nivel más exacto. Por lo anterior, se pueden emprender o diseñar acciones de conservación enfocadas a áreas más específicas dentro del estado de Oaxaca, México.

AbstractWild specimens of Vanilla planifolia represent a vital part of this resource primary gene pool, and some plants have only been reported in Oaxaca, Mexico. For this reason, we studied its geographical distribution within the state, to locate and describe the ecological characteristics of the areas where they have been found, in order to identify potential areas of establishment. The method comprised four stages: 1) the creation of a database with herbarium records, 2) the construction of the potential distribution based on historical herbarium records for the species, using the model of maximum entropy (MaxEnt) and 22 bioclimatic variables as predictors; 3) an in situ systematic search of individuals, based on herbarium records and areas of potential distribution in 24 municipalities, to determine the habitat current situation and distribution; 4) the description of the environmental factors of potential ecological niches generated by MaxEnt. A review of herbarium collections revealed a total of 18 records of V. planifolia between 1939 and 1998. The systematic search located 28 plants distributed in 12 sites in 95 364 Km2. The most important variables that determined the model of vanilla potential distribution were: precipitation in the rainy season (61.9 %), soil moisture regime (23.4 %) and precipitation during the four months of highest rainfall (8.1 %). The species potential habitat was found to be distributed in four zones: wet tropics of the Gulf of Mexico, humid temperate, humid tropical, and humid temperate in the Pacific. Precipitation oscillated within the annual ranges of 2 500 to 4 000 mm, with summer rains, and winter precipitation as 5 to 10 % of the total. The moisture regime and predominating climate were udic type I (330 to 365 days of moisture) and hot humid (Am/A(C) m). The plants were located at altitudes of 200 to 1 190 masl, on rough hillsides that generally make up the foothills of mountain systems, with altitudes of 1 300 to 2 500 masl. In natural conditions, distribution of the species is not limited to high evergreen forests, since it was also found in mountain mesophyll and tropical evergreen forests. The location of new specimens of V. planifolia in its wild condition reduces the potential distribution area by 66 %. This area is fragmented into three geographically separated areas. Habitat reduction was due to the increased number of located plants that define the environmental conditions into a more accurate level. Conservation actions can thus be designed and implemented, focusing on more specific areas within the state of Oaxaca, Mexico.

[Potential distribution and geographic characteristics of wild populations of Vanilla planifolia (Orchidaceae) Oaxaca, Mexico]. / Distribución potencial y características geográficas de poblaciones silvestres de Vanilla planifolia (Orchidaceae) en Oaxaca, México.

Wild specimens of Vanilla planifolia represent a vital part of this resource primary gene pool, and some plants have only been reported in Oaxaca, Mexico. For this reason, we studied its geographical distribution within the state, to locate and describe the ecological characteristics of the areas where they have been found, in order to identify potential areas of establishment. The method comprised four stages: 1) the creation of a database with herbarium records, 2) the construction of the potential distribution based on historical herbarium records for the species, using the model of maximum entropy (MaxEnt) and 22 bioclimatic variables as predictors; 3) an in situ systematic search of individuals, based on herbarium records and areas of potential distribution in 24 municipalities, to determine the habitat current situation and distribution; 4) the description of the environmental factors of potential ecological niches generated by MaxEnt. A review of herbarium collections revealed a total of 18 records of V. planifolia between 1939 and 1998. The systematic search located 28 plants distributed in 12 sites in 95 364 Km(2). The most important variables that determined the model of vanilla potential distribution were: precipitation in the rainy season (61.9 %), soil moisture regime (23.4 %) and precipitation during the four months of highest rainfall (8.1 %). The species potential habitat was found to be distributed in four zones: wet tropics of the Gulf of Mexico, humid temperate, humid tropical, and humid temperate in the Pacific. Precipitation oscillated within the annual ranges of 2 500 to 4 000 mm, with summer rains, and winter precipitation as 5 to 10 % of the total. The moisture regime and predominating climate were udic type I (330 to 365 days of moisture) and hot humid (Am/A(C) m). The plants were located at altitudes of 200 to 1 190 masl, on rough hillsides that generally make up the foothills of mountain systems, with altitudes of 1 300 to 2 500 masl. In natural conditions, distribution of the species is not limited to high evergreen forests, since it was also found in mountain mesophyll and tropical evergreen forests. The location of new specimens of V. planifolia in its wild condition reduces the potential distribution area by 66 %. This area is fragmented into three geographically separated areas. Habitat reduction was due to the increased number of located plants that define the environmental conditions into a more accurate level. Conservation actions can thus be designed and implemented, focusing on more specific areas within the state of Oaxaca, Mexico.

Effect of freeze-drying and production process on the chemical composition and fatty acids profile of avocado pulp / Efecto del liofilizado y del proceso de producción en la composición química y el perfil de ácidos grasos de la pulpa de aguacate

Freeze-drying technology is the best dehydration process to preserve shelf-life and allowing avocado to maintain its sensorial and nutritional characteristics. The aim of this work was to determine if the freeze-drying and production condition have an effect on the nutritional quality of the avocado pulp grown in rain-fed and irrigation orchards. Four treatments were applied: non-freeze-dried rain-fed fruits, non-freeze-dried irrigation fruits, freeze-dried rain-fed fruits and freeze-dried irrigation fruits. Results showed that the fruit is made up of 71.4%, 16%, and 12.6% pulp, seed and skin, respectively. The pulp is made up of 71.51%, 19.96%, 2.81%, 0.51% and 1.51% water, lipids, ashes, crude fiber and protein, respectively. Avocado oil is composed by 61%, 18.8%, 11.6% and 7% oleic, palmitic, linoleic, and palmitoleic fatty acids, respectively. The freeze-drying decreased the linoleic acid by 1.43 g/100g. Under rain-fed conditions 4% and 13% less total fat and oleic fatty acid are produced than in irrigation conditions. We conclude that freeze-dried avocado pulp shows slight changes in their nutritional quality.

La tecnología de liofilización es el mejor proceso de deshidratación para mantener mayor vida de anaquel y conservar las propiedades nutricionales y sensoriales de la pulpa del aguacate. El objetivo de este estudio fue determinar si el liofilizado y condición de producción tienen un efecto sobre la calidad nutrimental de la pulpa de aguacate cultivado en huertas de riego y temporal. Se aplicaron 4 tratamientos: frutos de temporal no liofilizado, frutos de riego no liofilizado, frutos liofilizados de temporal y frutos liofilizados de riego. Los resultados muestran que el fruto está compuesto por 71.39, 16 y 12.6% de pulpa, hueso y cascara respectivamente. La pulpa está compuesta por 71.51, 19.96, 2.81, 0.51 y 1.5 % de humedad, lípidos, cenizas, fibra cruda y proteína, respectivamente. El aceite del aguacate está constituido de 61. 18.8, 11.6 y 7% de ácidos grasos oleico, palmítico, linoléico y palmitoleico, respectivamente. El liofilizado disminuyó 1.43 g/100 g de ácido linoléico. Bajo condiciones de temporal se produce 4 y 13% menos grasa total y ácido graso oleico que en condiciones de riego. Se concluye que la pulpa del aguacate liofilizada presenta ligeros cambios en su calidad nutrimental.

Physiological performance, yield, and quality of dry bean seeds under drought stress / Comportamiento fisiológico, rendimiento y calidad de semilla de frijol sometido a sequía / Comportamento fisiológico, rendimento e qualidade da semente do feijão submetido à seca

Net photosynthesis (A), respiration (RE), stomatal conductance (gs), transpiration rate (E), yield, and its components, as well as physical and physiological quality of seeds were evaluated on dry bean (Phaseolus vulgaris L.) plants cv. ‘Otomí’, subjected to drought stress during the stages of flowering (F), pod formation (PF) and seed filling (SF). After 3 days under drought stress, gs, E and A decreased by more than 50% at F, PF and SF, respectively; after 10 days of stress, there was total inhibition of those processes, whereas the maximum reductions showed by RE were 42, 62, and 85% in F, PF and SF, respectively. Drought stress induced seed yield reductions of 10, 57, and 50% at F, PF and SF, respectively. High yield losses at PF and SF were caused by reductions in the number of seeds and pods per plant and seeds per pod. At the SF stage the loss in yield was moderate, because at this stage the plants were able to form new leaves and delay pod formation until water stress was over. The physiological quality was not affected by drought stress, even though the weight of 1000 seeds was reduced by about 10%.

Se evalúo la fotosíntesis neta (A), respiración (RE), conductancia estomática (gs), tasa de transpiración (E), rendimiento y sus componentes, así como la calidad física y fisiológica de semillas de plantas de frijol (Phaseolus vulgaris L.) cv. ‘Otomí’ sometidas a sequía durante las etapas de floración (F), formación de vaina (FV) y llenado de semilla (LLS). Después de 3 días de sequia, gs, E y A disminuyeron en más de 50% en F, FV y LLS, respectivamente; después de 10 días de estrés hubo inhibición total de estos procesos, mientras que las reducciones máximas mostradas por RE fueron de 42, 62 y 85% en F, FV y LLS, respectivamente. La sequía propició reducciones en el rendimiento de semilla de 10, 57 y 50% en F, FV y LLS, respectivamente. Las altas pérdidas de rendimiento en FV y LLS se debieron a las reducciones en número de semillas, de vainas por planta y de semillas por vaina. En F la disminución en rendimiento fue moderada, debido a que en esta etapa las plantas formaron nuevas hojas y retardaron la formación de vainas cuando terminó la sequía. La calidad fisiológica de las semillas no resultó afectada por la sequía, aun cuando el peso de 1000 semillas tuvo una reducción de casi 10%.

Avaliou-se a fotossíntese neta (A), respiração (RE), condutância estomática (gs), taxa de transpiração (E), rendimento e seus componentes, assim como a qualidade física e fisiológica de sementes de plantas de feijão (Phaseolus vulgaris L.) cv. ‘Otomí’ submetidas à seca durante as etapas de floração (F), formação de vagens (FV) e enchimento da semente (LLS). Depois de 3 dias de seca, gs, E e A diminuiram em mais de 50% em F, FV e LLS, respectivamente; depois de 10 dias de estresse houve inibição total destes processos, enquanto que as reduções máximas mostradas por RE foram de 42, 62 e 85% em F, FV e LLS, respectivamente. A seca propiciou reduções no rendimento da semente de 10, 57 e 50% em F, FV e LLS, respectivamente. As altas perdas de rendimento em FV e LLS foram devido às reduções em número de sementes, de vagens por planta e de sementes por vagem. Em F a diminuição no rendimento foi moderada, devido a que nesta etapa as plantas formaram novas folhas e retardaram a formação de vagens quando terminou a seca. A qualidade fisiológica das sementes não resultou afetada pela seca, mesmo quando o peso de 1000 sementes teve uma redução de quase 10%.

Conocimiento campesino en la selección de variedades de haba (vicia faba l.) en la Sierra Norte de puebla México / Rural knowledge in the selection of varieties of faba bean (vicia faba l.) In the Sierra North of puebla, Mexico / Conhecimento camponês na seleção de variedades de fava (vicia faba l.) na Serra Norte de puebla México

Se estudió los caracteres relacionados con el ambiente, la planta y la semilla, que considera el campesino en la selección de variedades de haba (Vicia faba L.) y se analizó el proceso de generación y transmisión del conocimiento campesino, así como su importancia en el uso, manejo y conservación de la semilla. Se usó un enfoque cuantitativo mediante un cuestionario y el método descriptivo de encuesta muestral, y un enfoque cualitativo mediante observación y entrevista directa a 74 campesinos del grupo étnico náhuatl del Municipio de Tlatlauquitepec, Sierra Norte de Puebla, México. El tamaño de muestra se determinó por componente de marco de lista. Los principales caracteres relacionados con el ambiente en el cultivo de haba, considerados por el campesino, son humedad (80%), color (74%) y fertilidad del suelo (62%); en planta, resistencia a heladas (81%), sanidad (76%) y precocidad (55%); y en grano, sanidad (93%), y sanidad y tamaño (55%). Los campesinos que seleccionan cuatro o más caracteres relacionados con ambiente, planta y semilla, son quienes contribuyen al mejoramiento genético de la especie, por integrar una mayor cantidad de conocimientos y ejercer mayor presión selectiva. El conocimiento campesino sobre los caracteres de haba se genera por un proceso complejo de interrelaciones, en que se conjugan saberes sobre su entorno, el comportamiento de la especie en determinada condición y un conocimiento heredado perfeccionado por la experimentación. En este proceso va implícita la conservación de la diversidad de recursos genéticos locales de la especie.

This study is aimed at documenting the characters related with the environment, the plant and the seed that peasants take into account in the selection of local varieties of faba bean (Vicia faba L.). The process of generation, and transmission of rural knowledge and their use importance, handling and seed conservation were analyzed. A quantitative approach was used through a questionnaire and the descriptive method of sampling survey; a qualitative approach was also used, by observation and direct interviews to 74 peasants from the Municipality of Tlatlauquitepec, Sierra Norte de Puebla, Mexico. The main characters related with the environment in the faba bean crop that are considered by the peasant are soil humidity (80%), soil colour (74%) and fertility (62%); in relation to the plant features, cold resistance (81%), plant health (76%), and precocity (55%); and in relation to grain aspect, grain health (93%), and grain health and size (55%). The peasants selecting four or more characters of the beans, in relation to the environment, plant and seed, contributed more to the improvement of the species, as they integrated more knowledge and exerted higher selective pressure. The rural knowledge about the characters in faba bean is created through a complex process of interrelations, where knowledge is conjugated with environment and species behaviour at one particular condition, and an inherited knowledge transmitted by generations that is constantly improved by experimentation. In this process is implicit the conservation of local genetic resources of the species.

Foram estudados os caracteres relacionados com o ambiente, a planta e a semente, considerados pelo camponês na seleção de variedades de fava (Vicia faba L.) e se analisou o processo de geração e transmissão do conhecimento camponês, bem como sua importância no uso, manejo e conservação da semente. Utilizou-se um enfoque quantitativo mediante um questionário e o método descritivo de pesquisa amostral, e um enfoque qualitativo mediante observação e entrevista direta a 74 camponeses do grupo étnico nahuatl do Município de Tlatlauquitepec, Serra Norte de Puebla, México. O tamanho da amostra foi determinado por componente de marco de lista. Os principais caracteres relacionados com o ambiente no cultivo de fava, considerados pelo camponês, são umidade (80%), cor (74%) e fertilidade do solo (62%); em planta, resistência a geadas (81%), sanidade (76%) e precocidade (55%); e em grão, sanidade (93%), e sanidade e tamanho (55%). Os camponeses que selecionam quatro ou mais caracteres relacionados com ambiente, planta e semente, são aqueles que contribuem ao melhoramento genético da espécie, por integrar una maior quantidade de conhecimentos e por exercer maior pressão seletiva. O conhecimento camponês sobre os caracteres da fava é gerado por um processo complexo de inter-relações, nas que se conjugam saberes sobre seu entorno, o comportamento da espécie em determinada condição e um conhecimento herdado aperfeiçoado pela experimentação. Neste processo vá implícita a conservação da diversidade de recursos genéticos locais da espécie.

Intercambio de gases y relaciones hídricas durante el retraso de la senescencia foliar de trigo (Triticum aestivum L) por la citocinina bap / Gas exchange and water relations during delay of leaf senescence in wheat (Triticum aestivum L) by cytokinin bap

Se estudió el efecto de la citocinina 6-bencilaminopurina (BAP) en el intercambio de gases y relaciones hídricas de Triticum aestivum L. durante el retraso de la senescencia foliar en invernadero. Plántulas de 21 días después de la siembra (DDS) fueron asperjadas con BAP 0,1mM o agua (testigo) cada 3 días por 20 días. El retraso de senescencia foliar en las plantas tratadas con BAP fue monitoreado mediante cuantificación de clorofila y proteína soluble total. El intercambio de gases se estimó mediante conductancia estomática (gs) y tasa de fijación de CO2. Las relaciones hídricas se evaluaron midiendo el potencial de agua total (YA) y sus componentes, osmótico (Ys) y de turgencia (Yt), cada 5 días por 20 días. Las hojas con BAP mostraron mayor concentración de clorofila y proteína total que el control tras 26 DDS, diferencias que aumentaron con el tiempo y a los 41 DDS fueron 7 veces mayores que el control. La gs registró valores no significativamente diferentes al estado verde pre-senescente. Estas respuestas se asociaron con tasas mayores de fijación de CO2, con concentraciones cercanas a las hojas verdes pre-senescentes (6,2μmol·CO2·m-²·s-¹). El YA se mantuvo constante bajo BAP y Ys fue significativamente menor que en los testigos, favoreciendo la retención de solutos en el citoplasma de hojas con retraso de senescencia. El Yt de las hojas tratadas fue mayor que su respectivo testigo de 31 a 41 DDS. Por tanto, la citocinina BAP promovió el mantenimiento de la tasa de fijación de CO2 y las relaciones hídricas durante el retraso de la senescencia foliar.

Phosphoenolpyruvate carboxykinase in developing pea seeds is associated with tissues involved in solute transport and is nitrogen-responsive.

The aim of this work was to investigate the occurrence of phosphoenolpyruvate carboxykinase (PEPCK) in developing pea (Pisum sativum) seeds in relation to their nitrogen supply. PEPCK was present throughout development, with the peak of PEPCK protein and activity in the seed coat and cotyledons preceding protein accumulation in the cotyledons. It showed a different developmental pattern from enzymes involved in amino acid metabolism (phosphoenolpyruvate carboxylase, glutamine synthetase and glutamate dehydrogenase). Immunolocalization showed that PEPCK was present in parts of the developing seed that are involved in the transport and metabolism of assimilates. Early in development, it was associated with the inner integument of the ovule, the endospermic cytoplasm and the outer cells of the embryo. In the middle of development, around the peak of activity, PEPCK was abundant at the outer surface of the developing cotyledons, in the embryonic axis and in the vasculature of the seed coat. Later in development, PEPCK was associated with the embryonic leaf primordia and meristem and cortex of the radicle. PEPCK protein was strongly induced in vitro in the seed coat by nitrate, ammonium and asparagine, in the cotyledons by asparagine and in planta by the supply of nitrogen, which led to an increase in asparagine secretion by empty seed coats. It is suggested that PEPCK is involved in the metabolism of nitrogenous solutes in developing pea seeds.